Locking or security seals are used to prevent tampering with and unauthorized entry to or operation of various items. Examples of items on which locking or security seals are used are doors of ocean containers, truck trailers, freight cars, equipment cabinets, high-voltage switches etc.
A typical seal includes a metal bolt, or a flexible cable having a head on one end and a solid tip on the other end, and a lock body for receiving one end of the metal bolt or a solid tip of the flexible cable. Once the end of the metal bolt or solid tip of the flexible cable is inserted into the lock body, the metal bolt or solid tip is retained and restrained from removal by a locking mechanism in the lock body.
These seals also provide an indication of unauthorized attempts made to enter or operate an item through tampering with or defeating the seal. The indication of any tampering of the seals is normally through visual observation of the seal. However, a sophisticated interloper may easily gain entry by cutting the seal and later reposition the parts back in such a way to make it appear that the seal has not been tampered with. Visually observing the seal thus will fail to indicate the tampering of the seal.
In the U.S. Pat. No. 5,127,687 referred to in FIG. 1, a tamper indicating seal 10 of the type having a bolt 14 retained in a lock body 16 is shown. The lock body 16 is surrounded by a shroud 50 of frangible, brittle material and provided with a grooved outer surface 60 and flanged entrance way 57 for receiving and surrounding the bolt end 18b, whereby the shroud 50 is easily fractured, thus providing visual indication of tampering.
Any attempt to drive the lock body 16 and a fragment of the shaft 18 out of the bore 54 of the lock body 16 is prevented by interference between shoulders 57c, 18c. A further determined attempt will fracture or crack the shroud 50 or flange 57.
Due to the nature of the material of the shroud 50, breakage or chipping may occur from mishandling of the seal 10 instead of unauthorized tampering. Furthermore, a sophisticated interloper is able to cut the bolt 14 and weld the metal bolt 14 back without causing any breakage to the shroud 50. Visual inspection or observation may not be able to indicate any tampering since the shroud 50 is intact.
Therefore, there is a need for an improvement on tamper indicating device that is able to better indicate any tampering of the seal despite sophisticated interloper's attempts to undo any indication of tampering as cited above.